Background Metabolic dysfunction-associated steatotic liver disease (MASLD) is highly prevalent in type 2 diabetes mellitus (T2DM) and amplifies cardiovascular and metabolic burden. Elevated low-density lipoprotein cholesterol (LDL-C) is a key driver of atherosclerotic cerebrovascular stenosis, and MASLD-mediated hepatic lipid dysregulation is closely linked to LDL-C metabolism. One-hour postload plasma glucose (1h-PG) reflects early beta-cell dysfunction and may synergistically contribute to cerebrovascular injury alongside the MASLD/FIB-4 phenotype. Methods This single-center retrospective cross-sectional study enrolled 312 treatment-naïve adults with newly diagnosed T2DM, of whom 278 completed a standardized 75-g oral glucose tolerance test (OGTT; age 24–78 years). The primary outcome was ultrasound-confirmed MASLD combined with age-specific FIB-4 screening positivity (age <65 years: FIB-4 ≥1.30; age ≥65 years: FIB-4 ≥2.00). Secondary outcomes included elevated LDL-C (≥3.4 mmol/L) and cerebrovascular stenosis (≥50% luminal narrowing in major intracranial or extracranial arteries). Results Overall, 199 participants (71.6%) had MASLD and 64 (23.0%) met the primary outcome. Those meeting the primary outcome had significantly higher 1h-PG (17.7 ± 3.7 vs. 14.9 ± 3.8 mmol/L; P<0.001), with an adjusted OR of 1.15 per 1-mmol/L increment (95% CI 1.05–1.26; P = 0.003). Elevated LDL-C was present in 73 participants (26.3%) and cerebrovascular stenosis in 49 (17.6%). The composite group of high 1h-PG (≥Q3) plus MASLD/FIB-4 positivity had the highest stenosis rate (34.8% vs. 6.0%), with an adjusted OR of 2.61 (95% CI 1.23–5.55; P = 0.012). Adding LDL-C attenuated the OR from 3.42 to 2.61 (~24%), indicating partial mediation. The AUC improved from 0.661 (1h-PG alone) to 0.726 (combined model). Conclusions In newly diagnosed T2DM, elevated 1h-PG was associated with MASLD/FIB-4 positivity; their combination was further linked to higher LDL-C and increased cerebrovascular stenosis risk, with LDL-C potentially acting as a partial mediator. The combined model showed improved discriminative ability, though validation in larger multicenter cohorts remains warranted.